EXTIRPATION OF ORGAN ANLAGEN 



251 



OBSERVATIONS AJIP EXPEBIMENTAL DATA : 



Under each sut-heading for Extirpations, follow the development of each emhryo with 

 a series of sketches. The first drawing should be made Immediately after the excision, 

 and the last one after the excised area has heen completely reformed, whether or not It Is 

 regenerated. The time elapsed (days) and, the medium and temperature should all he noted. 

 (See section on "Wound Healing".) 



TAIL BUD 



\ 

 HYPOPHYSIS 



RANA PIPIENS 



STAGE 16 

 CLOSED NEURAL TUBE 



ORGAN FIELDS 



NEURAL TUBE 



PRONEPHROS 



. * 



FORE LIMB 



EAR 



HIND LIME 



YOLK M ASSj_ _' 



BALANCER 



AMBLYSTOMA PUNCTATUM 



STAGE 31 



\ 



HYPOPHYSIS 



